RhB Adsorption Performance of Magnetic Adsorbent Fe_3O_4/RGO Composite and Its Regeneration through A Fenton-like Reaction

Adsorption is one of the most effective technologies in the treatment of colored matter containing wastewater. Graphene related composites display potential to be an effective adsorbent. However, the adsorption mechanism and their regeneration approach are still demanding more efforts. An effective magnetically separable absorbent, Fe3O4 and reduced graphene oxide(RGO) composite has been prepared by an in situ coprecipitation and reduction method. According to the characterizations of TEM, XRD, XPS, Raman spectra and BET analyses, Fe3O4 nanoparticles in sizes of 10-20 nm are well dispersed over the RGO nanosheets, resulting in a highest specific area of 296.2 m2/g. The rhodamine B adsorption mechanism on the composites was investigated by the adsorption kinetics and isotherms. The isotherms are fitting better by Langmuir model, and the adsorption kinetic rates depend much on the chemical components of RGO. Compared to active carbon, the composite shows 3.7 times higher adsorption capacity and thirty times faster adsorption rates. Furthermore,with Fe3O4 nanoparticles as the in situ catalysts, the adsorption performance of composites can be restored by carrying out a Fenton-like reaction, which could be a promising regeneration way for the adsorbents in the organic pollutant removal of wastewater.

Composition Optimization and Microstructure Design in MOFs-Derived Magnetic Carbon-Based Microwave Absorbers:A Review

Magnetic carbon-based composites are the most attractive candidates for electromagnetic(EM)absorption because they can terminate the propagation of surplus EM waves in space by interacting with both electric and magnetic branches.Metal-organic frameworks(MOFs)have demonstrated their great potential as sacrificing precursors of magnetic metals/carbon composites,because they provide a good platform to achieve high dispersion of magnetic nanoparticles in carbon matrix.Nevertheless,the chemical composition and microstructure of these composites are always highly dependent on their precursors and cannot promise an optimal EM state favorable for EM absorption,which more or less discount the superiority of MOFs-derived strategy.It is hence of great importance to develop some accompanied methods that can regulate EM properties of MOFs-derived magnetic carbon-based composites e ectively.This review comprehensively introduces recent advancements on EM absorption enhancement in MOFs-derived magnetic carbon-based composites and some available strategies therein.In addition,some challenges and prospects are also proposed to indicate the pending issues on performance breakthrough and mechanism exploration in the related field.

Preparation of Chelating Polymer Grafted Magnetic Adsorbent and Its Application for Removal of Pb(Ⅱ) Ions

A novel magnetic chelating adsorbent （CPMS） with iminodiacetate functionality was prepared by polymerization of glycidyl methacrylate-iminodiacetic acid （GMA-IDA） monomer with N, N-methylenebisacrylamide as crosslinker in the presence of monodisperse magnetic silica microspheres （MS）. CPMS was characterized by IR, SEM, VSM and TGA. The experimental results revealed that MS was embedded in the gel polymer, but the morphology of CPMS was irregular. The saturation magnetization for CPMS was found to be 28.4 emu/g, and the percentage of GMA-IDA polymer grafted on MS was about 46.5%. CPMS were shown to be efficient for the removal of Pb（II） ions at pH 3.0 - 6.0, and the adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 54.4 mg？g？1 at pH 5.0. Moreover, the adsorption rate of CPMS was fast and it took about 5 minutes to achieve adsorption equilibrium in aqueous solution of lower lead ions concentration.

Recyclable hydrolyzed polymers of intrinsic microporosity-1/Fe_(3)O_(4) magnetic composites as adsorbents for selective cationic dye adsorption

Polymers of intrinsic microporosity shows great potential for dye adsorption and magnetic Fe_(3)O_(4) are easy to be separated.In this work,hydrolyzed polymers of intrinsic microporosity-1/Fe_(3)O_(4) composite adsorbents were prepared by phase inversion and hydrolysis process for cationic dye adsorption.The chemical structure and morphology of the composite adsorbents were systematically characterized by several characterization methods.Using methylene blue as the target dye,the influences of solution pH,contact time,initial dye concentration,and system temperature on the methylene blue adsorption process were investigated.The incorporation of Fe_(3)O_(4) particle into hydrolyzed polymers of intrinsic microporosity-1 endow the adsorbent with high magnetic saturation(20.7 emu·g^(–1))which allows the rapid separation of the adsorbent.Furthermore,the adsorption process was simulated by adsorption kinetics,isotherms and thermodynamics to gain insight onto the intrinsic adsorption mechanism.In addition,the composite adsorbents are able to selectively adsorb cationic dyes from mixed dyes solution.Hydrolyzed polymers of intrinsic microporosity/Fe_(3)O_(4) shows only a slight decrease for methylene blue adsorption after 10 adsorption/regeneration cycles,demonstrating the outstanding regeneration performance.The high adsorption capacity,outstanding regeneration ability,together with simple preparation method,endow the composite adsorbents great potential for selective removal of cationic dyes in wastewater system.

Facile Synthesis of the Magnetic Metal Organic Framework Fe_3O_4@UiO-66-NH_2 for Separation of Strontium

A magnetic metal organic framework（MMOF） was synthesized and used to separate Sr^2＋ in aqueous solution. The shape and structure of prepared Fe3O4@UiO-66-NH2 were characterized, and the absorbed concentration of strontium was determined through inductively coupled plasma mass spectrometry. The results indicated that Fe3O4 and UiO-66-NH2 combined through chemical bonding. The experimental adsorption results for separation of Sr^2＋ in aqueous solution indicated that the adsorption of Sr^2＋ to Fe3O4@UiO-66-NH2 increased drastically from pH 11 to pH 13. The adsorption isotherm model indicated that the adsorption of Sr^2＋ conformed to the Freundlich isotherm model（R2 = 0.9919）. The MMOF thus inherited the superior qualities of magnetic composites and metal organic frameworks, and can easily be separated under an external magnetic field. This MMOF thus has potential applications as a magnetic adsorbent for low level radionuclide （90）Sr.

Magnetically responsive porous materials for efficient adsorption and desorption processes

Magnetically responsive porous materials possess unique properties in adsorption processes such as magneticinduced separation and heat generation in alternating magnetic fields, which greatly facilitates recycling procedures, favors long-term operation, and improves desorption rate, making conventional adsorption processes highly efficient. With increasing interest in magnetic adsorbents, great progress has been made in designing and understanding of magnetically responsive porous materials varying from monoliths to nanoscale particles used for adsorption including oil uptake, removal of hazardous substances from water, deep desulfurization of fuels, and CO2 capture in the past few years. Therefore, a review summarizing the advanced strategies of synthesizing these magnetically responsive adsorbents and the utilization of their magnetism in practical applications is highly desired. In this review, we give a comprehensive overview of this emerging field, highlighting the strategies of exquisitely incorporating magnetism to porous materials and subtly exploiting their magnetic responsiveness. Further innovations for fabricating or utilizing magnetic adsorbents are expected to be fueled. The potential opportunities and challenges are also discussed.

QuEChERS-超高效液相色谱-串联质谱分析鱼中13种全氟及多氟烷基化合物

全氟及多氟烷基化合物(PFASs)广泛存在于全球环境水体中,鱼类等水产品的摄入可能是人类接触PFASs的重要来源,因此亟需建立鱼类产品中PFASs的高效、准确分析技术。本研究以磁性纳米材料为净化吸附剂,基于QuEChERS方法,建立了鱼类产品中13种PFASs的超高效液相色谱-串联质谱(UHPLC-MS/MS)分析方法。实验分别考察了萃取溶剂类型、净化吸附剂(Fe_( 3)O_( 4)-TiO_( 2)和N-丙基乙二胺(PSA))用量对PFASs回收率的影响,确定了最佳样品前处理条件。采用Luna Omega C18色谱柱(100 mm×2.1 mm,1.6μm)进行分离,利用电喷雾电离(ESI)源,在多反应监测(MRM)模式下采集质谱数据,内标法定量。在优化的实验条件下,13种PFASs在0.01~50μg/L内具有良好的线性关系,相关系数(R)≥0.9973,检出限为0.001~0.023μg/L,定量限为0.003~0.078μg/L。在低、中、高3个加标水平(0.5、10、100μg/kg)下,13种PFASs的加标回收率为78.1%~118%,日内精密度为0.2%~11.1%,日间精密度为0.8%~8.7%。将该方法应用于实际样品分析,所有鱼样品中均有PFASs检出,分别为全氟辛酸、全氟辛基磺酸、全氟十一烷酸、全氟十二烷酸和全氟十三烷酸,各自的检出总含量为0.327~1.728μg/kg。本方法前处理过程简单且灵敏度高,适用于鱼类产品中PFASs的分析。

基于低场核磁共振原位监测的煤岩甲烷吸附解吸动力学研究

吸附态甲烷在深部煤岩储层微纳米孔隙中占主导地位,研究其在吸附解吸中的扩散特征对于煤层气开发的预测与现场实施具有重要指导意义。基于自主研发搭建的体积法吸附原位低场核磁试验系统,研究了沁水盆地无烟煤样品的吸附解吸动力学特性,实现了吸附态甲烷在扩散过程中的原位动态监测。结果表明:核磁法所测吸附态有效扩散系数与体积法所测微孔扩散系数呈现相同演化规律:即在吸附过程中,吸附态甲烷的扩散系数随压力的增加呈现先增加后减小的规律;在解吸过程中,其随压力的减小而单调递减。该演化规律表明微孔填充过程中气体扩散分为两个阶段:气体压力小于6 MPa时,分子扩散及努森扩散占主导地位;当气体压力超过6 MPa时,吸附相表面扩散占主导地位。该实验设计为煤层气高效开发提供了重要的实验方法及数据,对实验室核磁共振分析设备的教学以及针对特定科学问题进行的设备升级改造具有重要指导意义。

离子液体基磁性固相萃取-高效液相色谱法测定饮料中的合成色素

国家对合成色素使用量有严格限量标准,有效萃取和测定食品中合成色素对保障食品安全有重要意义。采用红外光谱、透射电镜和振动样品磁强计等对合成的聚合离子液体修饰的磁性纳米材料的结构、形貌和磁性进行了表征,将此磁性纳米材料作为磁性固相萃取(magnetic solid-phase extraction,MSPE)吸附剂,研究了其对4种合成色素(柠檬黄、日落黄、诱惑红和亮蓝)的萃取性能,结合MSPE与高效液相色谱技术,对影响萃取效率的吸附剂用量、吸附时间、解吸时间和盐的含量等参数进行了优化。研究结果表明:根据吸附剂对典型阴/阳离子型染料的吸附结果,推断4种合成色素的有效萃取归因于吸附剂与分析物之间存在的强静电引力以及π-π和疏水作用等多重作用;在吸附剂用量为10 mg、吸附时间为20 min、解吸剂为1 mL乙腈/盐酸(体积比9∶1)和解吸时间为10 s的优化萃取条件下,4种色素具有良好的线性(决定系数为0.9922~0.9975),检出限(S/N=3)和定量限(S/N=10)分别为1~3μg/L和2.5~10μg/L;该方法能成功用于碳酸饮料健力宝和菠萝啤中合成色素的测定,3个质量浓度下(日落黄、诱惑红和亮蓝均为25、100、250μg/L,柠檬黄为50、200、500μg/L)的加标回收率为71.4%~113.0%,相对标准偏差小于10.9%(n=3)。本研究为食品中合成色素的分析提供了一种很有前景的样品前处理方法。

黄芪废渣磁性碳化吸附剂制备及其对水中四环素的吸附动力学研究

以黄芪废渣和氯化铁混合物为原料,采用限氧热解法在700℃焙烧,制备黄芪废渣磁性碳化吸附剂(HC),研究其对四环素的吸附性能,考察的实验条件主要有四环素浓度、溶液pH、吸附剂用量、震荡时间。得出实验结论:在四环素溶液浓度140.0 mg/L、溶液pH5.6、黄芪废渣磁性碳化吸附剂的添加量2.5 g/L、震荡搅拌时间50 min时,吸附率最高可达94.1%,吸附量为52.696 mg/g。动力学分析实验结果表明黄芪废渣磁性碳化吸附剂(HC)对水中四环素的吸附过程与伪二级动力学模型更为一致。

磁性纳米粒子在中药提取分离的研究进展

磁性纳米粒子(Magnetic Nanoparticles,MNPs)因其超顺磁性、磁响应性、生物兼容性和高比表面积等特点,在中药领域引起学者的广泛关注。简要介绍了MNPs提取分离技术的原理及优势,并重点总结了它在中药提取分离的应用情况。同时,指出了MNPs分离技术目前存在的问题和研究现状。目的是为了后续大规模生产和应用MNPs提取分离中药的有效成分提供坚实的理论基础和有益的参考。

磁性聚氨基噻唑吸附剂脱除水体Hg^(2+)性能

聚多巴胺(PDA)辅助负载聚氨基噻唑(PAT)法制备了磁性颗粒吸附剂Fe_(3)O_(4)@SiO_(2)@PDA-PAT。对吸附剂进行了XRD、VSM、TG、SEM、XPS、EDS和Zeta电位等表征分析,考察了吸附剂对Hg^(2+)的吸附性能。结果表明,Fe_(3)O_(4)@SiO_(2)@PDA-PAT具有超顺磁性,在pH小于2时Zeta电位为正,pH大于2时Zeta电位为负。在303 K和Hg^(2+)浓度为50 mg/L模拟废水中,当pH为1.3和5.0时,Hg^(2+)的平衡吸附量分别为121.9 mg/g和153.1 mg/g。在强酸(如pH 1.3)和弱酸(如pH 5.0)环境下Fe_(3)O_(4)@SiO_(2)@PDA-PAT吸附Hg^(2+)的过程均是自发过程,且符合二级动力学模型和Langmuir等温吸附模型。强酸环境下(如pH 1.3)Fe_(3)O_(4)@SiO_(2)@PDA-PAT吸附Hg^(2+)是焓驱动的放热过程,弱酸(如pH 5.0)环境下是熵驱动的吸热过程。用2 mol/L混酸(盐酸和硝酸摩尔比为1∶1)作为解吸液可使Hg^(2+)解吸率达91%以上。在303 K、pH 1.3、Hg^(2+)浓度20 mg/L条件下,当Na^(+)、K^(+)、Mg^(2+)、Ca^(2+)、Cu^(2+)、Zn^(2+)、Ni^(2+)质量浓度为Hg^(2+)的20倍时,Fe_(3)O_(4)@SiO_(2)@PDA-PAT的Hg^(2+)平衡吸附量分别下降了33.2%、32.1%、20.6%、26.7%、21.2%、29.6%、17.8%。在模拟海水下,Hg^(2+)吸附量下降40.9%。Fe_(3)O_(4)@SiO_(2)@PDA-PAT具有较好的Hg^(2+)选择性,具有净化海水脱除重金属的应用潜力。

冻融条件下粉质黏土中吸附水和自由水动态变化规律

为了研究粉质黏土中吸附水和自由水在冻融时的动态变化特征,探索土体冻融过程中土水之间物理过程。采用新型分层核磁测量技术,开展了含水量(质量分数)分别为21.1%,16.8%和12.0%的粉质黏土在封闭条件下的冻融试验,并采用电子显微镜扫描了冻融后不同深度土体的微观结构。试验结果表明:随着土体冻结过程持续,不同深度土体中自由水和吸附水均减少,且冻结区和非冻结区的自由水相对减少量均大于吸附水相对减少量;土样融化时不同深度土体中自由水和吸附水均增加;此外冻融作用导致冻结区吸附水减少,自由水增加;而未冻结区的吸附水和自由水均减少;冻融后冻结区的孔隙数量和孔隙体积增加,而未冻结区孔隙数量和孔隙体积减小。冻结过程中土体吸附水和自由水动态变化差异与水分子作用势的不均匀空间分布有关;冻融前后土体吸附水和自由水的重分布是水分迁移和土体微观结构变化共同作用的结果。

S Zorb废吸附剂磁分离回用技术分析

国内某炼油厂S Zorb装置产生大量极具回收价值的废吸附剂,部分未来得及参与反应,部分参与反应的流程较短。本文结合具体案例,开展试验,分析S Zorb废吸附剂磁分离回用技术的可行性。其间根据S Zorb吸附剂颗粒的物理化学性质和磁分离选矿理论,讨论新鲜剂和再生剂的磁选原理,提出磁分离工艺,开展小型试验,确定磁分离回用的技术效果,然后进行工业试验。研究表明,S Zorb废吸附剂的磁分离回用技术可实现工业化应用,从而显著降低S Zorb装置运行费用,减少危废排放量。

磁性粒子Fe_(3)O_(4)@SiO_(2)掺杂铝基锂吸附剂的制备及性能研究

用Fe_(3)O_(4)@SiO_(2)磁性粒子和铝基吸附剂复合制备一种层状磁性铝基吸附剂(MLDHs),利用XRD、SEM等对MLDHs的结构形貌进行表征。考察了MLDHs对溶液中锂离子的吸附性能,研究了吸附过程的吸附等温线、吸附动力学以及循环稳定性。结果表明:MLDHs适合在p H为3~5的溶液中进行锂吸附,其吸附容量最高达到12.42 mg/g。在混合离子溶液中,MLDHs对锂离子表现出良好的选择性和优先吸附。经过5次吸附-解吸循环后,MLDHs的吸附容量未发生明显变化。吸附等温线和吸附动力学分别符合Langmuir模型和准二级动力学模型。

Synthesis of amino-silane modified magnetic silica adsorbents and application for adsorption of flavonoids from Glycyrrhiza uralensis Fisch

Magnetic separation technology was applied in the separation of flavonoids from the licorice root in this work. Licorice flavonoids (LF) displayed a remarkable array of biological and pharmacological activities. The magnetic adsorbents with functional -NH2 groups were synthesized by immobilization of amino-silane on the surface of the magnetic silica supports, which were prepared by co-precipitation method. The adsorption and desorption characteristics of the magnetic adsorbents for the separation of LF have been evaluated. The purity of an enriched extract with this method was 16.7% while the crude extract only had about 6.8% purity. Therefore, it can be concluded that these kinds of magnetic adsorbents have selectivity to the flavonoids to some extent. The affinity selectivity of the adsorbents is based on the formation of hydrogen bonding between the -NH2 on the magnetic adsorbents and -OH,-CO on the flavonoids.

Magnetically modified microbial cells:A new type of magnetic adsorbents

Microbial cells, either in free or immobilized form, can be used for the preconcentration or removal of metal ions, organic and inorganic xenobiotics or biologically active compounds. Magnetic modification of these cells enables to prepare magnetic adsorbents that can be easily manipulated in difficult-to-handle samples, such as suspensions, in the presence of external magnetic field. In this review, typical examples of magnetic modifications of microbial cells are presented, as well as their possible applications for the separation of organic xenobiotics and heavy metal ions.

Ferrimagnetic ceramic adsorbents for cleanup of H_2S from exhaust gases

Adsorbents that exhibit magnetic properties in addition to other required process-relevant characteristics open up new perspectives for the dry reduction and/or elimination of HES and other sulfur compounds from exhaust gases. These adsorbents eliminate the sulfur compounds from exhaust gases by virtue of their coatings and their magnetic property which makes it possible the use of magnetically assisted and stabilized fluidization in an externally applied magnetic field. In the present paper, the feasibility of the sorptive function of porous ceramic ferrimagnetic beads is ensured by sol-gel coating of zinc oxide without the formation of Zn-Fe-oxides and without considerable decrease of available pore volume. The results of material characterization by SEM, Auger electron spectroscopy, X-ray and mercury-porosity measurements and the loading capacity of a HES/N2 model gas are presented and discussed. The resulting HES loading of the functionalized adsorbent beads is more than 10 times larger than that of the starting material. @ 2007 Chinese Society of Particuolo^v and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V.

注CO_(2)提高页岩吸附甲烷采收率核磁共振实验

明确CO_(2)作用下页岩对CH_(4)的吸附解吸规律,对提高页岩气采收率具有重要意义。在明确目标页岩孔隙结构的基础上,引入核磁共振测试技术,分别开展了注CH_(4)和注CO_(2)吸附解吸实验,定量表征了CH_(4)的绝对吸附量,并研究了CO_(2)对页岩中CH_(4)吸附解吸的影响规律。结果表明:页岩中的CH_(4)以页岩表面的吸附态、孔隙中的游离态和颗粒之间的自由态赋存;核磁共振法计算的CH_(4)绝对吸附量大于热重法测定的过剩吸附量;CO_(2)能够解吸摩尔分数为21.8%~33.2%的吸附态CH_(4);吸附态CH_(4)解吸后会滞留在孔隙中成为游离态,但无法从孔隙中逸出成为自由态;注CO_(2)提高吸附气采收率的同时还应辅以二次水力压裂或CO_(2)干法压裂技术,以提高游离态CH_(4)向自由态的转化效率。研究成果可为提高页岩吸附CH_(4)采收率提供参考和借鉴。

磁性木质素基活性炭吸附亚甲基蓝的特性研究

为了探索磁性木质素基活性炭对亚甲基蓝的吸附性能和机制,采用化学共沉淀法制备木质素基磁性活性炭,考察了该磁性活性炭对亚甲基蓝的吸附性能。结果表明:该活性炭吸附亚甲基蓝的过程符合Langmuir吸附等温模型,吸附动力学符合用Elovich模型。磁性木质素基活性炭吸附亚甲基蓝是化学吸附为主的单分子层吸热过程。